Friday, May 11, 2012

On a previous episode, we tested using plastic thread forming screws as fasteners for 3D printed parts. While they work great for some applications, they can only be removed and inserted a limited number of times before they destroy the hole and they are somewhat limited in their holding strength.

We have been hard at work the last few weeks developing some new products, and found this an interesting solution to the problem.

Since you also have to buy machine screws, they are a little expensive at $0.15 each, in quantities of 100. These brass inserts perform better than expected. The soldering iron tip makes them incredibly easy to install and the holding strength is more than sufficient for anything you would be 3D printing in plastic.

In a properly sized hole with a slight chamfer we were unable to pull out the inserts with our planned test methodology, and the tests were deemed successful.

Spotted this on Make Blog. I work primarily with wood, but may have to try some of these inserts. I assume they could also be glued in.

Sometimes I need to screw something into wood that will be removed enough that the wood may eventually strip out. What I've been doing is to drill a hole large enough to insert an unexpanded plastic drywall anchor. Then instead of using the screw included with the anchor, I use a smaller diameter one; just big enough so that the threads grip well with minimal expansion of the anchor.

I've had great luck with this. Great holding power, no split wood, and if an anchor ever strips out it should be replaceable; though this has never happened.

While not as small and elegant as these threaded inserts, perhaps this may be of utility in fused filament parts too; with the advantage that you can get them at any hardware store.